Costs for membrane cleaning – key aspects in membrane plant operation

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Details

Title Costs for membrane cleaning – key aspects in membrane plant operation
Person and role
Description Fouling has been identified as one of the most critical parameters for the slow integration of membrane technology in the industry since early days. In recent years, important progress has been made to reduce the impact on fouling and cleaning of membrane and thus their impact on plant operation and consequently the capital (CAPEX) and operating expenditures (OPEX) of membrane processes. This presentation will show the interactions between pre-treatment, operating conditions, fouling and cleaning and how the aspects can be optimized with regard to industrial membrane processes considering both technical and economic aspects.
The challenges of cleaning and fouling in biorefineries will be focus of the first part of the presentation. In the second part different approaches to reduce fouling and improve cleaning will be introduced, while in the final part an application study will used to demonstrate approaches optimizing fouling and cleaning and thus improving OPEX and CAPEX for a membrane system in the starch-based sweetener industry.
In biorefineries, cleaning has to be integrated part of the membrane plant operation and depending on the duty for product loop a cleaning every day or every other day is required, while for membrane plants on the water the sequence of cleaning might be less. In particular, for new application determining the cleaning frequency, number of cleaning steps and cleaning cycle length is quite arbitrary. Each time a cleaning cycle is initiated part of the complete plant has to be taken out of operation. To compensate for the capacity loss during downtime extra membrane area has to be installed, in case of 4-hours a day cleaning cycle this means that 17% additional membrane area has to be installed which impacts the plant CAPEX. Further, a typically cleaning cycle consists further of 3 – 4 chemical/enzymatic cleaning steps plus additional flushing steps. Additionally, each cleaning cycle requires cleaning agents, water, heating and electricity plus the reduction of membrane life cycle as result of regular cleaning – resulting costs which have a significant impact on the OPEX. Hence, optimizing plant operation to minimize fouling and/or optimize the cleaning protocol can have a significant impact on plant OPEX and CAPEX.
An initial step to reduce fouling is to identify fouling materials and their sources plus the fouling mechanisms. Often a suitable pre-treatment step, e.g. a self-cleaning strainer, might already lead to a significant reduction in fouling material. Alternatively/additionally, the use of constant trans-membrane pressure for high flux applications, the use of vibrating or rotating modules can help to minimize fouling.
However, to avoid fouling completely is often not possible and thus cleaning is essential. In this case a review of the cleaning protocols with regard to e.g. cleaning temperature, concentration and type of cleaning chemicals, length and frequency of cleaning step might offer some potential improvements of the cleaning.
In order to highlight the opportunities of improving plant performance by reducing fouling and improving cleaning an application study related to the front-end of a corn-based biorefinery will be discussed. In this part of the process corn starch is converted by saccarification to starch-based sweetener. Directly after saccarification, these sweeteners contain impurities such as retrograded starch, proteins and fats which have to be removed before further processing. In order to achieve this recently a hybrid process consisting of a decanter and an ultrafiltration process with spiral would elements has been developed. Important developments for this new process was the introduction of pre-filters before ultrafiltration elements, the use of low fouling regenerate cellulose membrane and an improved cleaning cycle. The improvement did not only reduced OPEX and CAPEX but also the sweetener quality achieved compared to other membrane based alternatives.
In summary this presentation will demonstrate the important impact fouling and cleaning can have on the CAPEX and OPEX of membranes. The approaches highlighted in this study can support the optimization of membrane process performance and consequently the long-term sustainability of membrane processes in biorefineries.
Date/period

2017 Jun 262017 Jun 30

Research areas and keywords

UKÄ subject classification

  • Chemical Engineering

Keywords

  • Membranes, Fouling, Cleaning
Related organisations
Fouling has been identified as one of the most critical parameters for the slow integration of membrane technology in the industry since early days. In recent years, important progress has been made to reduce the impact on fouling and cleaning of membrane and thus their impact on plant operation and consequently the capital (CAPEX) and operating expenditures (OPEX) of membrane processes. This presentation will show the interactions between pre-treatment, operating conditions, fouling and cleaning and how the aspects can be optimized with regard to industrial membrane processes considering both technical and economic aspects.
The challenges of cleaning and fouling in biorefineries will be focus of the first part of the presentation. In the second part different approaches to reduce fouling and improve cleaning will be introduced, while in the final part an application study will used to demonstrate approaches optimizing fouling and cleaning and thus improving OPEX and CAPEX for a membrane system in the starch-based sweetener industry.
In biorefineries, cleaning has to be integrated part of the membrane plant operation and depending on the duty for product loop a cleaning every day or every other day is required, while for membrane plants on the water the sequence of cleaning might be less. In particular, for new application determining the cleaning frequency, number of cleaning steps and cleaning cycle length is quite arbitrary. Each time a cleaning cycle is initiated part of the complete plant has to be taken out of operation. To compensate for the capacity loss during downtime extra membrane area has to be installed, in case of 4-hours a day cleaning cycle this means that 17% additional membrane area has to be installed which impacts the plant CAPEX. Further, a typically cleaning cycle consists further of 3 – 4 chemical/enzymatic cleaning steps plus additional flushing steps. Additionally, each cleaning cycle requires cleaning agents, water, heating and electricity plus the reduction of membrane life cycle as result of regular cleaning – resulting costs which have a significant impact on the OPEX. Hence, optimizing plant operation to minimize fouling and/or optimize the cleaning protocol can have a significant impact on plant OPEX and CAPEX.
An initial step to reduce fouling is to identify fouling materials and their sources plus the fouling mechanisms. Often a suitable pre-treatment step, e.g. a self-cleaning strainer, might already lead to a significant reduction in fouling material. Alternatively/additionally, the use of constant trans-membrane pressure for high flux applications, the use of vibrating or rotating modules can help to minimize fouling.
However, to avoid fouling completely is often not possible and thus cleaning is essential. In this case a review of the cleaning protocols with regard to e.g. cleaning temperature, concentration and type of cleaning chemicals, length and frequency of cleaning step might offer some potential improvements of the cleaning.
In order to highlight the opportunities of improving plant performance by reducing fouling and improving cleaning an application study related to the front-end of a corn-based biorefinery will be discussed. In this part of the process corn starch is converted by saccarification to starch-based sweetener. Directly after saccarification, these sweeteners contain impurities such as retrograded starch, proteins and fats which have to be removed before further processing. In order to achieve this recently a hybrid process consisting of a decanter and an ultrafiltration process with spiral would elements has been developed. Important developments for this new process was the introduction of pre-filters before ultrafiltration elements, the use of low fouling regenerate cellulose membrane and an improved cleaning cycle. The improvement did not only reduced OPEX and CAPEX but also the sweetener quality achieved compared to other membrane based alternatives.
In summary this presentation will demonstrate the important impact fouling and cleaning can have on the CAPEX and OPEX of membranes. The approaches highlighted in this study can support the optimization of membrane process performance and consequently the long-term sustainability of membrane processes in biorefineries.
2017 Jun 262017 Jun 30

Event (Conference)

Title34th EMS Summer School
Period2017/06/262017/06/30
LocationPalaestra and Bäckaskog Castle
CityLund/Fjälkinge
CountrySweden